Bixenon upgrade
 

I know that there are tons of discussions ongoing but need a simple answer :D Im about to buy a 2012 facelift w204 but its with the ordinary halogen headlights. So can upgarde to the bixenon ones and is it plug play? Thank you in advance for your answers and excuse me for posting it again :)

I have the same desire to update my 2014. What I've seen is there is an aftermarket kit of unknown quality/complexity. Have not seen anyone who did it by getting OEM used lights and related parts, the way I'd prefer to do it. Apparently either way there's quite a bit of wiring that's different from the std halogen lights, so not a plug and play.

Check this out:

Brulliant. And is there a way for fitting OEM follow me ones? Im a little bit more fan of those fits :D

It's possible but it will be very expensive because the OEM Bi-xenon headlights are quite expensive and would still need to do some retrofitting and configuring using MB-specific diagnostic tools (Xentry) to flip the car, software-wise, from halogen to xenon.
I looked into this myself when I got my car and the effort and money involved were not worth for me. I went with high quality bi-xenon plug-and-plug headlights for $600 and I couldn't be happier. Sure I don't have the turning headlights and the auto HI/LO feature, but they're not economically feasible for me at 3x the cost I paid.